1. Field
Example embodiments relate to a display apparatus that uses an oxide diode, and more particularly, to a display apparatus that uses an oxide diode having a nano-rod structure, e.g., a nano-rod structure formed of zinc oxide.
2. Description of the Related Art
Many different kinds of display apparatuses have been developed. One of the representative display apparatus may be a liquid crystal display (LCD). However, in the case of the LCD, in order to display an image on a screen, a backlight unit must be formed on a rear side of a liquid crystal panel, and be in a ‘turn ON’ state while the display is in operation. Accordingly, the backlight unit continuously consumes power. Thus, an LCD may consume a relatively large amount of power compared to other displays.
Also, in the case of an LCD, there may be a relatively large optical loss of light that may be emitted from the backlight unit in a process of passing through a polarizing plate, a liquid crystal layer, and a color filter. Thus, only a portion of light emitted from the backlight unit may be transmitted to the viewers. For this reason, an amount of light greater than light actually used may be required. In practice, in the case of LCD, light recognized by the viewer's eyes may be about 3% of the initial light emitted from the backlight unit, and the efficiency of light may be relatively low. Due to the relatively low optical efficiency, overall power consumption may be further increased.
As a next generation display apparatus, an organic light emitting diode (OLED) is being studied. Display apparatuses that use the OLED may have a wider viewing angle and a shorter response time. Also, the OLEDs may be formed to be thin, and thus, may be bended. Therefore, the OLEDs may be applied to flexible displays. However, an organic light emitting material used in the OLED may have a limited lifespan due to the characteristics of the organic material. An organic light emitting material that emits blue light having a lifetime of about 15,000 hours may have only a half of the lifetime (about 30,000 hours) required for a conventional flat panel TV.
Also, as yet, OLEDs may have a drawback of low light emission efficiency. In order to be realized as a display, the organic light emitting material must have a brightness of about 250 Cd/m2 when emitting light. The organic light emitting material that emits blue light currently may have an efficiency of about 15 Cd/A. Thus, in order to obtain a desired brightness, a relatively large amount of power consumption may be required.
Furthermore, the OLED must be manufactured in a bottom emitting structure that may have a relatively large optical loss. In the case of the bottom emitting structure, a light emission area may be reduced due to a thin film transistor region formed under the light emission region for controlling a light emission operation of the organic light emitting material, and also, light must pass a thick glass substrate on a bottom of the OLED, and thus, an additional optical loss may be caused. In the case of a top emission type OLED, because light may be emitted through a transparent upper electrode formed right above the organic light emitting material, such optical loss may not be initiated. However, if a transparent electrode is formed on the organic light emitting material, the organic light emitting material may be damaged and may be more easily degraded in the course of forming the transparent electrode.